An optically active compound represented by the formula (2)
wherein each symbol is as defined below, is known to be useful as an intermediate for producing a medicament, a pesticide and the like, since it can be converted to, for example, an optically active hexahydrofurofuranol derivative.
Concerning a production method of an optically active compound represented by the formula (2), non-patent document 1 discloses that an optically active 4-chloro-3-hydroxy-2-methylbutanal can be obtained, for example, by reacting chloroacetaldehyde with propanal in the presence of an enzyme.